Epoxy resin compositions, prepreg, and fiber-reinforced composite materials

Abstract

This invention relates to an epoxy resin composition for fiber-reinforced composite materials, which contains the following constituent components (A), (B), and (C). Component (A) contains at least one poly-naphthalene-based epoxy resin, component (B) contains at least one alicyclic epoxy resin and/or a divinylarene diepoxide resin, and component (C) contains at least one amine curing agent. This epoxy resin composition, containing a specific combination of particular types of epoxy resin and curatives, provides high heat resistance and high flexural modulus under extreme environmental conditions. More particularly, a cured resin prepared by the epoxy resin composition offers well balanced mechanical properties that are suitable for preparing fiber-reinforced composite materials useful in aircraft components, spacecraft components, automobile components, artificial satellites components, industrial components, and the like.

1 . An epoxy resin composition for a fiber-reinforced composite material comprising component (A), component (B), and component (C), wherein the epoxy resin composition when cured has a wet Tg of at least 205° C. and a hot/wet flexural modulus of at least 2.3 GPa, and wherein:
 component (A) comprises at least one poly-naphthalene-based epoxy resin; 
 component (B) comprises at least one liquid epoxy resin having a viscosity of less than 1 Pa·s at 25° C.; and 
 component (C) comprises at least one amine curing agent. 
 
     
     
         2 . The epoxy resin composition according to  claim 1 , wherein component (B) comprises at least one of (B1) at least one alicyclic epoxy resin represented by Formula (I) which is present in an amount of up to 15 PHR of total epoxy resin in the epoxy resin composition, or (B2) at least one divinylarene dioxide represented by Formula (II) which is present in an amount of up to 40 PHR of total epoxy resin in the epoxy resin composition: 
       
         
           
           
               
               
           
         
         wherein n is an integer of 0 or 1; each A is a cycloaliphatic group independently selected from the group consisting of cycloalkyl groups and cycloalkenyl groups having 4 to 8 carbon atoms; each X is independently selected from the group consisting of a hydrogen atom and an oxygen atom attached to adjacent carbon atoms of a cycloaliphatic group to form an epoxy group; Y, if present, is selected from the group consisting of a direct bond, —SO 2 —, —C(=O)O—,—C(═O)—, —O—, —C(=O)NH—, C 1  to C 6  alkyl groups, C 1  to C 6  alkoxyl groups, cycloalkyl groups, and aryloxyl groups, wherein these groups are optionally employed individually or different groups are optionally employed in combination as Y; each R 1  is independently selected from the group consisting of a hydrogen atom, a glycidyl group, a glycidyl ether group, a glycidyl ester group, and a cycloalkyl group having 4 to 7 carbon atoms directly attached at least one of the A groups; Ar is selected from the group consisting of aryl groups; and each R 2  is independently selected from the group consisting of a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group, subject to the proviso that the alicyclic epoxy resin represented by Formula (I) contains at least two epoxy groups per molecule. 
       
     
     
         3 . The epoxy resin composition according to  claim 2 , wherein component (B) comprises at least one alicyclic epoxy resin represented by Formula (I). 
     
     
         4 . The epoxy resin composition according to  claim 2 , wherein component (B) comprises at least one divinylarene dioxide represented by Formula (II). 
     
     
         5 . The epoxy resin composition according to  claim 4 , wherein component (B) comprises one or more divinylarene dioxides selected from the group consisting of divinylbenzene dioxides, divinylnaphthalene dioxides, divinylbiphenyl dioxides, divinyldiphenylether dioxides, and mixtures thereof. 
     
     
         6 . The epoxy resin composition according to  claim 2 , wherein component (B1) and component (B2) are present in amounts effective to provide a ratio of component (B1): component (B2) of from 0:40 to 15:0 PHR of total epoxy resin. 
     
     
         7 . The epoxy resin composition according to  claim 2 , wherein component (B1) is present in an amount of from 3 to 15 PHR of total epoxy resin. 
     
     
         8 . The epoxy resin composition according to  claim 2 , wherein component (B2) is present in an amount of from 3 to 40 PHR of total epoxy resin. 
     
     
         9 . The epoxy resin composition according to  claim 1 , wherein component (A) comprises at least one poly-naphthalene-based epoxy resin with an EEW greater than 150 g/eq which is present in an amount of 20 to 60 PHR of total epoxy resin. 
     
     
         10 . The epoxy resin composition according to  claim 1 , wherein component (C) comprises at least one aromatic polyamine. 
     
     
         11 . The epoxy resin composition according to  claim 9 , wherein component (C) consists of at least one diaminodiphenyl sulfone which is present in an amount which provides an AEW/EEW ratio of from 0.4 to 1.0. 
     
     
         12 . The epoxy resin composition according to  claim 1 , wherein the epoxy resin composition further comprises component (D) and component (E), wherein:
 component (D) comprises at least one latent acid catalyst; and   component (E) comprises at least one glycidyl ether epoxy resin or glycidyl amine epoxy resin containing at least two epoxy groups per molecule which is not an alicyclic epoxy resin according to Formula (I) or a divinylarene dioxide according to Formula (II).   
     
     
         13 . The epoxy resin composition according to  claim 12 , wherein component (D) comprises at least one onium salt catalyst. 
     
     
         14 . The epoxy resin composition according to  claim 12 , wherein component (D) comprises at least one onium salt catalyst represented by Formula (III): 
       
         
           
           
               
               
           
         
         wherein R 1  represents a hydrogen atom, a hydroxyl group, an alkoxyl group, or a group represented by Formula (IV): 
       
       
         
           
           
               
               
           
         
         wherein Z represents an alkyl group, an alkoxyl group, a phenyl group or a phenoxy group, all of which may have one or more substituents, each of R 2  and R 3  independently represents a hydrogen atom, a halogen atom, or an alkyl group, each of R 4  and R 5  independently represents an alkyl group, an aralkyl group or an aryl group, each of which may have one or more substituents, and X −  represents SbF 6   − , PF 6   − AsF 6   − , or BF 4   − . 
       
     
     
         15 . The epoxy resin composition according to  claim 12 , wherein the epoxy resin composition comprises an amount of component (D) which is 0.1 to 5 PHR of total epoxy resin in the epoxy resin composition. 
     
     
         16 . The epoxy resin composition according to  claim 12 , wherein the epoxy resin composition comprises an amount of component (E) which is at most 70 PHR of total epoxy resin in the epoxy resin composition. 
     
     
         17 . The epoxy resin composition according to  claim 1 , additionally comprising at least one thermoplastic resin. 
     
     
         18 . The epoxy resin composition according to  claim 17  wherein the at least one thermoplastic resin comprises a polyethersulfone. 
     
     
         19 . The epoxy resin composition according to  claim 1 , wherein the epoxy resin composition when cured has a water absorption less than 3.3 wt %. 
     
     
         20 . A prepreg comprising carbon fibers impregnated with an epoxy resin composition in accordance with  claim 1 . 
     
     
         21 . A carbon fiber-reinforced composite material obtained by curing a prepreg in accordance with  claim 20 . 
     
     
         22 . A carbon fiber-reinforced composite material comprising a cured resin product obtained by curing a mixture comprised of an epoxy resin composition in accordance with  claim 1  and carbon fibers.